Does anyone use Loctite or thread lock on thei axel bolts? Any pro's or con's? Also noticed there's several dozen versions of the gunk from light to heavy duty and oil and water resistant... whew.

Blue works and is removable. Red pretty much has to be heated with a torch to get it loose. Green wicks into threads that all ready have a bolt in them. These are the only ones I have used. If would use the blue, but if you disassemble your bug for transport, keep a small wire brush handy to get the dried up crap off of the bolts before you try to reassemble- can cause cross threading.

Board or buggy?

Assuming you got the Loctite lipstick devices and not tubes of liquid, then Red should be put on things you never plan on undoing again :D Blue is for stuff that you don't want coming undone unintentionally, but will want to remove one day ... like Heli-B said.
Depending on the application, I'd run the correct size tap and die over the parts but for an axle bolt I'd just make sure it's clean, put a tiny dab on and go for it.
Remember, less is more

FYI, Silver Loctite is used to stop different metals binding or corroding together, especially aluminum heads and exhaust bolts :D

I just use a giant combination wrench and check the axle bolts each time I go out. Takes about 15 secs.

Long time ago, before using a locknut between the axle and wheel I used to have problems with axle bolts loosening.
I tried overtorquing but eventually damaged the wheels.

I then tried the blue threadlock which prevented the bolts from loosening but using stainless bolts in a stainless axle eventually led to thread damage.
I later used plumber's tape (you know the white teflon tape to stop pipes leaking at the threaded joints).
This worked a treat and never had a problem undoing axle bolts or damaging threads again.

Best method of course is to use a locknut between the axle & wheel but that isn't always possible depending on what kind of buggy and axle bolts you have..

Usually you will only have a problem with one wheel coming loose. The natural rotation of the wheel unscrews the axle bolt. Especially if your bearings are somewhat warn or binding....or seized. The other wheel will naturally tighten up from the same problems. Over tightening doesn't always work and could do more damage to the wheel/bearings, especially if your internal bearing spacer is not the perfect length (or not being used). Over tightening could put abnormal wear on your bearings causing them to wear out faster than normal. If you are not using a bearing spacer, over tightening will put a lot of wear on the wheel shoulder causing your wheel to heat up (if the bearings start to wear / bind) and could destroy your wheel.

Teflon tape works great and is easy to remove. Blue locktite is recommended but as mentioned, you need to clean the old gunk off before re-assembling again - only takes a couple seconds with a wire brush. To make sure you don't cross thread, only put the blue locktite on the threads about a half inch behind the starting of the bolt and let it dry before inserting. That way you will have good threads going in easy to prevent cross threading. Red locktite could lock your bolt in solid and may not make it possible to remove - not recommended..

As mentioned, a jam nut between the wheel and axle is best.